Content of total polyphenols and antioxidant activity in selected varieties of onion (Allium cepa L.)

Abstract

Onion (Allium cepa L.) is one of the most important vegetable crops widely consumed in the world. The bulb onion is grown as fresh shoots and as bulbs for consuming uncooked, cooked, and pickled or production of seed and sets. They can be eaten raw, boiled, steamed and roasted. Onion has high nutritional value. Onions are a good source of vitamins, minerals and major component like polyphenols, flavonoids, fructooligosaccharides, thiosulfinates and other sulfur compounds. Polyphenols belong to significant antioxidants in human diet. Antioxidant compounds (polyphenols, flavonoids) scavenge free radicals, inhibit the oxidative mechanisms that lead to degenerative diseases. Antioxidant compounds in food play an important role as a health protecting factor. Onions have a wide range of beneficial properties for human health, such as anti-cholesterolaemic, anti-mutagenic and antioxidant capacity. In this work we evaluated content of total polyphenols and antioxidant activity in selected varieties of onion. Samples of plant material we collected at the stage of full maturity in the locality of Pružina. Pružina is locality without negative influences and emission sources. Total polyphenols content and antioxidant activity were measured in six varieties of onion, namely in red variety (Red matté), in yellow varieties (Boston, Bingo, Sherpa) and white varieties of onion (Diamond, White dry). The content of the total polyphenols was determined by using the Folin-Ciocalteu reagent (FCR). Antioxidant activity was measured by using a compound DPPH˙. In the present experiment it was detected, that total polyphenols content in samples ranges from 142.01 mg.kg -1 GAE (white variety of onion-White dry) to 1083.04 mg.kg -1 GAE (red variety of onion-Red matté). Statistically significant highest value of total polyphenols (1083.04 mg.kg -1 GAE) was recorded in variety Red matté. Another indicator that has been evaluated and compared was the antioxidant activity. The values of antioxidant activity were in interval from 7.74% to 41.67%. Based on the measured values of antioxidant activity in onion the samples can beclassified as follows: Red matté (41.67%) > Boston (25.77%) > Sherpa (24.34%) > Bingo (19.54%) > White dry (8.10%) > Diamond (7.74%).

INCREASING OF SELENIUM CONTENT AND QUALITATIVE PARAMETERS IN GARDEN PEA (Pisum sativum L.) AFTER ITS FOLIAR APPLICATION

“…Fratianni et al [2014] states for lentils variety San Gerardo 1098 µg g -1 , Colliano 1594 µg g -1 and for chickpea Sassano 147 µg g -1 , Castelcivita 183 µg g -1 . Our results are in contrary with experiments of Kavalcová et al [2014a], suggested that doses of the Se did not have significant effect on the content of polyphenols. In the trial with onion they applied Se in the form of sodium selenate in different form, there was applicated into soil.…”

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“…Our results are in contrary with experiments of Kavalcová et al [2014a], suggested that doses of the Se did not have significant effect on the content of polyphenols. In the trial with onion they applied Se in the form of sodium selenate in different form, there .…”

Investigation of phenolic compounds and antioxidant activity in red and yellow onions and a synergistic utilization of skin extract in modified atmosphere packaging of salmon (Salmo salar)

“…10 Polyphenols are a large group of chemical compounds with subgroups including flavonoids and anthocyanins. [11][12][13] Phenolic compounds may inhibit lipid oxidation as free radical scavengers and metal ion chelators. 14 Onions are well known as a rich source of polyphenols including flavonoids that increases the antioxidant capacity.…”

“…15 The high contents of onion flavonoids consist of quercetin aglycone and its glycosides. 12,15,16 Flavonoids tend to accumulate in outer peel (bulb skin) of onions.…”